/Engine/Source/Editor/ContentBrowserData/Public/ContentBrowserDataSource.h
If you override this then you are responsible foralldrag and drop handling (including the default move/copy behavior) via the HandleDrag functions below!
A custom drag operation, or null to allow another data source (or the default handler) to deal with it instead.
virtual [TSharedPtr](API\Runtime\Core\Templates\TSharedPtr)< [FDragDropOperation](API\Runtime\SlateCore\Input\FDragDropOperation) > CreateCustomDragOperation ( [TArrayView](API\Runtime\Core\Containers\TArrayView)< const [FContentBrowserItemData](API\Editor\ContentBrowserData\FContentBrowserItemData) > InItems )